1. Field of the Invention
This invention relates in general to tools for swaging or setting fastener collars around grooved fastener pins and particularly relates to a rotatable anvil and collet assembly formed with a work clearance zone for accessing hard to reach fasteners.
2. Description of Prior Developments
Tools used to swage fastener collars around fastener pins commonly include a hand-held tool body that houses a hydraulic cylinder within which a double acting piston is moved by hydraulic pressure to operate a collet and jaw assembly. An anvil is connected to the cylinder portion of the tool in surrounding relation to the collet for swaging the collar over the pin.
With the jaw assembly gripping a grooved fastener pin, the application of hydraulic pressure causes the tool cylinder to recoil relative to the piston. This causes the free or nose end of the anvil to travel axially along and over the fastener collar so as to swage the collar member into the grooves on the fastener pin. This swaging operation is sometimes referred to as setting a fastener.
Fasteners of the above noted type are used extensively in the aircraft industry to interconnect airframe structural members. These structural members can have various cross sectional configurations, such as U and J shaped channels. It is often necessary to locate the fasteners behind flanges formed on the structural members and in such cases the space required for accommodating the nose end of the fastener tool may be partially obstructed by the flanges.
In order to utilize such fasteners where space is limited, such as in the space between the flanges on a channel type structural member, various tools having offset nose assemblies have been developed. For example, U.S. Pat. Nos. 4,813,261 and 4,896,522 disclose push-pull tools having offset nose assemblies. In each of these patented arrangements the offset nose assembly is capable of rotary adjustment around the piston axis, such that the tool can be held in a relatively comfortable position by the tool operator. This is the case even when the channel member or other structural member is in an overhead location or in some other location where the tool operator would have to twist his or her arm or body if the offset nose assembly had a fixed, non-rotary mounting with respect to the tool body.
The tools shown in U.S. Pat. Nos. 4,813,261 and 4,896,522 perform satisfactorily in most situations. However, the offset nature of these nose assemblies tends to increase tool manufacturing costs. Also, the offsetting of the nose assemblies from the piston axis tends to introduce cantilever forces within the tool, as outlined in the specification of U.S. Pat. No. 4,813,261. As a result, the tool components have to be made somewhat thicker and stronger, thereby increasing the weight of the tool.
Light tool weight and small tool size are desirable characteristics for this type of tool because a lighter tool is easier to handle and manipulate. Moreover, a lighter tool can be used for a longer period of time before the tool operator experiences hand or wrist fatigue. Accordingly, a need exists for a light weight in-line rotatable nose assembly which is capable of accessing hard to reach fasteners.